The Xbox Music team at Microsoft last night released apps for iOS and Android and introduced free streaming in its Web application.

Xbox Music already had a 30 million song library, about 50 percent more than the 20 million boasted each by Spotify and Rdio. But it's now a more viable competitor to those services, with apps that extend it across the most popular mobile platforms.

The Web player at music.xbox.com and the app for Windows 8 were also upgraded with free streaming today. The free streaming for Web and Windows 8 will be unlimited for six months; it will then be limited to an unspecified number of hours. A paid subscription providing unlimited streaming will be available across all platforms, of course. Windows 8.1 users will also get a new feature that automatically creates playlists from the content of a webpage, as well as integration with Bing Smart Search to make music discovery easier.

Described in an announcement by Xbox Music GM Jerry Johnson, the iOS and Android apps provide access to streaming, but they don't have all the features Spotify and Rdio users enjoy. Microsoft says it will change that in the coming months, with an offline listening mode for iOS and Android and artist-based radio stations for iOS, Android, and the Web.

The iOS app is optimized for iPhone, but like any iPhone app, it can be run on an iPad in a scaled-up, not-so-great-looking version.

Xbox Music costs $9.99 for one month and $99.90 for 12 months, with a 30-day free trial available. An account is required to use the iOS and Android apps.